CROSSBOW
A crossbow including a center rail including a rail body and a riser, a first flexible limb coupled to the riser, a second flexible limb coupled to the riser, and a first cam mounted to the first flexible limb and rotatable around a first cam axis, and including a first draw string journal defining a first draw string plane of rotation perpendicular to the first cam axis, and a first power cable take-up journal extending in a direction perpendicular to the first draw string plane of rotation. The crossbow including a second cam mounted to the second flexible limb and rotatable around a second cam axis. The second cam including a second draw string journal defining a second draw string plane of rotation perpendicular to the second cam axis, and a second power cable take-up journal extending in a direction perpendicular to the second draw string plane of rotation.
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The present application is a continuation of U.S. patent application Ser. No. 17/972,437 entitled Crossbow, filed Oct. 24, 2022, which is a continuation of U.S. patent application Ser. No. 17/029,548 entitled Crossbow, filed Sep. 23, 2020, which is a continuation of U.S. patent application Ser. No. 16/258,982 entitled Crossbow, filed Jan. 28, 2019 (issued as U.S. Pat. No. 11,085,728), which is a continuation of U.S. patent application Ser. No. 15/395,835 entitled Crossbow, filed Dec. 30, 2016 (issued as U.S. Pat. No. 10,254,073), which is a continuation-in-part of U.S. patent application Ser. No. 15/294,993 entitled String Guide System For A Bow, filed Oct. 17, 2016 (issued as U.S. Pat. No. 9,879,936), which is a continuation-in-part of U.S. patent application Ser. No. 15/098,537 entitled Crossbow, filed Apr. 14, 2016 (issued U.S. Pat. No. 9,494,379), which claims the benefit of priority from U.S. Provisional Patent Application No. 62/244,932, entitled String Guide System For A Bow, filed Oct. 22, 2015; and Ser. No. 15/098,537 is a continuation-in-part of U.S. patent application Ser. No. 14/107,058 entitled String Guide System For A Bow, filed Dec. 16, 2013 (issued as U.S. Pat. No. 9,354,015), the entire disclosures of which are hereby incorporated by reference in their entirety.
FIELD OF THE INVENTIONThe present disclosure is directed to a crossbow and to a cabling system for a crossbow in which only the draw string crosses the center rail.
BACKGROUND OF THE INVENTIONBows have been used for many years as a weapon for hunting and target shooting. More advanced bows include cams that increase the mechanical advantage associated with the draw of the bowstring. The cams are configured to yield a decrease in draw force near full draw. Such cams preferably use power cables that load the bow limbs. Power cables can also be used to synchronize rotation of the cams, such as disclosed in U.S. Pat. No. 7,305,979 (Yehle).
With conventional bows and crossbows the draw string is typically pulled away from the generally concave area between the limbs and away from the riser and limbs. This design limits the power stroke for bows and crossbows.
In order to increase the power stroke, the draw string can be positioned on the down-range side of the string guides so that the draw string unrolls between the string guides toward the user as the bow is drawn, such as illustrated in U.S. Pat. No. 7,836,871 (Kempf) and U.S. Pat. No. 7,328,693 (Kempf). One drawback of this configuration is that the power cables can limit the rotation of the cams to about 270 degrees. In order to increase the length of the power stroke, the diameter of the pulleys needs to be increased. Increasing the size of the pulleys results in a larger and less usable bow.
As the draw string 30 is moved from released configuration 32 of
Further rotation of the string guides 22 in the direction 36 causes the power cables 20 to contact the power cable take-up journal, stopping rotation of the cam. The first attachment points 24 may also contact the power cables 20 at the locations 34A, 38B (“38”), preventing further rotation in the direction 36. As a result, rotation of the string guides 22 is limited to about 270 degrees, reducing the length 40 of the power stroke.
BRIEF SUMMARY OF THE INVENTIONThe present disclosure is directed to a crossbow that includes a center rail including a rail body and a riser, a first flexible limb coupled to the riser, a second flexible limb coupled to the riser, and a first cam mounted to the first flexible limb and rotatable around a first cam axis. The first cam includes a first draw string journal defining a first draw string plane of rotation perpendicular to the first cam axis, and a first power cable take-up journal extending in a direction perpendicular to the first draw string plane of rotation. The crossbow further includes a second cam mounted to the second flexible limb and rotatable around a second cam axis. The second cam includes a second draw string journal defining a second draw string plane of rotation perpendicular to the second cam axis, and a second power cable take-up journal extending in a direction perpendicular to the second draw string plane of rotation. The crossbow further includes a draw string received in the first draw string journal and in the second draw string journal and secured to the first cam and the second cam, a first power cable coupled to the center rail and received in the first power cable take-up journal, and a second power cable coupled to the center rail and received in the second power cable take-up journal. The first cam and the second cam are configured so that the draw string unwinds from the first draw string journal and the second draw string journal as the crossbow is moved from a released configuration to a drawn configuration. The first cam is configured to rotate more than 270 degrees about the first cam axis as the crossbow is moved from the released configuration to the drawn configuration. The second cam is configured to rotate more than 270 degrees about the second cam axis as the crossbow is moved from the released configuration to the drawn configuration. The first power cable take-up journal of the first cam is configured to displace the first power cable away from the first draw string plane of rotation as the crossbow is moved from the released configuration to the drawn configuration. The second power cable take-up journal of the second cam is configured to displace the second power cable away from the second draw string plane of rotation as the crossbow is moved from the released configuration to the drawn configuration.
The present disclosure is also directed to a method of operating a crossbow including a center rail having a rail body and a riser, a first flexible limb coupled to the riser, a second flexible limb coupled to the riser, a first cam mounted to the first flexible limb and rotatable around a first cam axis, the first cam including a first draw string journal defining a first draw string plane of rotation perpendicular to the first cam axis and a first power cable take-up journal extending in a direction perpendicular to the first draw string plane of rotation, a second cam mounted to the second flexible limb and rotatable around a second cam axis, the second cam including a second draw string journal defining a second draw string plane of rotation perpendicular to the second cam axis and a second power cable take-up journal extending in a direction perpendicular to the second draw string plane of rotation, a draw string received in the first draw string journal and in the second draw string journal and secured to the first cam and the second cam, a first power cable coupled to the center rail and received in the first power cable take-up journal, and a second power cable coupled to the center rail and received in the second power cable take-up journal. The method includes rotating the first cam and the second cam more than 270 degrees to unwind the draw string from the first draw string journal and the second draw string journal as the crossbow is moved from a released configuration to a drawn configuration, wrapping the first power cable onto the first power cable take-up journal and displacing the first power cable away from the first draw string plane of rotation as the crossbow is moved from the released configuration to the drawn configuration, and wrapping the second power cable onto the second power cable take-up journal and displacing the second power cable away from the second draw string plane of rotation as the crossbow is moved from the released configuration to the drawn configuration.
In the reverse draw configuration 92 the draw string 114 is located adjacent down-range side 94 of the string guide system 70 when in the released configuration 116. In the released configuration 116 of
As illustrated in
The string guides 104 each include one or more grooves, channels or journals located between two flanges around at least a portion of its circumference that guides, a flexible member, such as a rope, string, belt, chain, and the like. The string guides can be cams or pulleys with a variety of round and non-round shapes. The axis of rotation can be located concentrically or eccentrically relative to the string guides. The power cables and draw strings can be any elongated flexible member, such as woven and non-woven filaments of synthetic or natural materials, cables, belts, chains, and the like.
As the first attachment points 106 rotate in direction 120, the power cables 102 are wrapped onto cams 126A, 126B (“126”) with helical journals 122A, 122B (“122”), preferably located at the respective axles 110. The helical journals 122 take up excess slack in the power cables 102 resulting from the string guides 104 moving toward each other in direction 124 as the axles 110 move toward each other.
The helical journals 122 serve to displace the power cables 102 away from the string guides 104, so the first attachment points 106 do not contact the power cables 102 while the bow is being drawn (see
As a result, the power stroke 132 is extended. In the illustrated embodiment, the power stroke 132 can be increased by at least 25%, and preferably by 40% or more, without changing the diameter of the string guides 104. The power stroke 132 can be in the range of about inches to about 20 inches. The present disclosure permits crossbows that generate kinetic energy of greater than 70 ft.-lbs. of energy with a power stroke of about 8 inches to about 15 inches. In another embodiment, the present disclosure permits a crossbow that generates kinetic energy of greater than 125 ft.-lbs. of energy with a power stroke of about 10 inches to about 15 inches.
In some embodiments, the geometric profiles of the draw string journals 130 and the helical journals 122 contribute to let-off at full draw. A more detailed discussion of cams suitable for use in bows is provided in U.S. Pat. No. 7,305,979 (Yehle), which is hereby incorporated by reference.
Draw string 162 is received in respective draw string journals (see e.g.,
First power cable 168A is secured to the first string guide 158A at first attachment point 170A and engages with a power cable take-up with a helical journal 172A (see
Second power cable 168B is secured to the second string guide 158B at first attachment point 170B and engages with a power cable take-up with a helical journal 172B (see
Draw string 314 extends between first and second string guides 316A, 316B (“316”). In the illustrated embodiment, the string guide 316A substantially as shown in
The first string guide 316A mounted to the first bow limb 312A and is rotatable around a first axis 318A. The first string guide 316A includes a first draw string journal 320A and a first power cable take-up journal 322A, both of which are oriented generally perpendicular to the first axis 318A. (See e.g.,
The second string guide 316B is mounted to the second bow limb 312A and rotatable around a second axis 318B. The second string guide 316B includes a second draw string journal 320B oriented generally perpendicular to the second axis 318B.
The draw string 314 it received in the first and second draw string journals 320A, 320B and is secured to the first string guide 316A at first attachment point 324. The draw string extends adjacent to the down-range side 306 to the second string guide 316B, wraps around the second string guide 316B, and is attached at the first axis 318A.
Power cable 324 is attached to the string guide 316A at attachment point 326. See
The string guides 366 are mounted to the bow limb 362 and are rotatable around first and second axis 368A, 368B (“368”), respectively. The string guides 366 include first and second draw string journals 370A, 370B (“370”) and first and second power cable take-up journals 372A, 372B (“372”); both of which are oriented generally perpendicular to the axes 368, respectively.
(See e.g.,
The draw string 364 is received in the draw string journals 370 and is secured to the string guides 316 at first and second attachment points 375A, 375B (“325”).
Power cables 374 are attached to the string guides 316 at attachment points 376A, 376B (“376”). See
In the illustrated embodiment, power cables wrap 374 onto the power cable take-up journal 372 and translates along the power cable take-up journals 372 away from the draw string journals 370, as the bow 150 is drawn from the released configuration 378 to the drawn configuration (see
The string guides disclosed herein can be used with a variety a bows and crossbows, including those disclosed in commonly assigned U.S. patent application Ser. No. 13/799,518, entitled Energy Storage Device for a Bow, filed Mar. 13, 2013 and Ser. No. 14/071,723, entitled DeCocking Mechanism for a Bow, filed Nov. 5, 2013, both of which are hereby incorporated by reference.
Draw String 501 is retracted to the drawn configuration 405 shown in
When in the drawn configuration 405 tension forces 409A, 409B on the draw string 501 on opposite sides of the string carrier 480 are substantially the same, resulting in increased accuracy. In one embodiment, tension force 409A is the same as tension force 409B within less than about 1.0%, and more preferably less than about 0.5%, and most preferably less than about 0.1%. Consequently, cocking and firing the crossbow 400 is highly repeatable. To the extent that manufacturing variability creates inaccuracy in the crossbow 400, any such inaccuracy are likewise highly repeatable, which can be compensated for with appropriate windage and elevation adjustments in the scope 414 (See
By contrast, conventional cocking ropes, cocking sleds and hand-cocking techniques lack the repeatability of the present string carrier 480, resulting in reduced accuracy. Windage and elevation adjustments cannot adequately compensate for random variability introduced by prior art cocking mechanism.
A cocking mechanism 484 (see e.g.,
In the drawn configuration 405 the distance 407 between the cam axles may be the range of about between about 6 inches to about 8 inches, and more preferably about 4 inches to about 8 inches. In one embodiment, the distance 407 between the axles in the drawn configuration 405 is less than about 6 inches, and alternatively, less than about 4 inches.
When in the drawn configuration 405 illustrated in
The small included angle 403 that results from the narrow separation 407 does not provide sufficient space to accommodate conventional cocking mechanisms; such as cocking ropes and cocking sleds disclosed in U S. Pat. No. 6,095,128 (Bednar); U.S. Pat. No. 6,874,491 (Bednar); U.S. Pat. No. 8,573,192 (Bednar et al.); U.S. Pat. No. 9,335,115 (Bednar et al.); and 2015/0013654 (Bednar et al.), which are hereby incorporated by reference. It will be appreciated that the cocking systems disclosed herein are applicable to any type of crossbow, including recurved crossbows that do not include cams or conventional compound crossbows with power cables that crossover.
Pivots 432A, 432B (“432”) attached to the riser 404 engage with the limbs 420 proximally from the mounting brackets 422. The pivots 432 provide a flexure point for the limbs 420 when the crossbow 400 is in the drawn configuration.
Cams 440A, 440B (“440”) are attached to the limbs 420 by axle mounts 442A, 442B (“442”). The cams 440 preferably have a maximum diameter 441 less than the power stroke (see e.g.,
In the illustrated embodiment, the axle mounts 442 are attached to the limbs 420 offset a distance 446 from the proximal ends 444A, 444B (“444”) of the limbs 420. Due to their concave shape, greatest width 448 of the limbs 420 (in both the drawn configuration and the release configuration) preferably occurs at a location between the axle mounts 442 and the pivots 432, not at the proximal ends 444.
The offset 446 of the axle mounts 442 maximizes the speed of the limbs 420, minimizes limb vibration, and maximizes energy transfer to the bolts 416. In particular, the offset 446 is similar to hitting a baseball with a baseball bat at a location offset from the tip of the bat, commonly referred to as the “sweet spot”. The size of the offset 446 is determined empirically for each type of limb. In the illustrated embodiment, the offset 446 is about 1.5 to about 4 inches, and more preferably about 2 to about 3 inches.
Tunable arrow rest 490 is positioned just behind the pocket 426. A pair of supports 492 are secured near opposite sides of the bolt 416 by fasteners 494. The supports 492 preferably slide in the plane of the limbs 420. As best illustrated in
The distal end 700 includes stem 706 that extends into hollow handle 708. Pins 710 permit the stem 706 to rotate a few degrees around pin 712 in either direction within the hollow handle 708. As best illustrated in
The string carrier 480 includes fingers 500 on catch 502 that engage the draw string 501. The catch 502 is illustrated in a closed position 504. After, firing the crossbow the catch 502 is retained in open position 505 (see
In the closed position 504 illustrated in
In one embodiment, a force necessary to overcome the friction at the interface 533 to release the catch 502 is preferably less than the biasing force applied to the sear 514 by the spring 511. This feature causes the sear 514 to return fully to the cocked position 524 in the event the trigger 558 is partially depressed, but then released before the catch 502 releases the draw string 501.
In another embodiment, a force necessary to overcome the friction at the interface 533 to release the catch 502 is preferably less than about 3.2%, and more preferably less than about 1.6% of the draw force to retain the draw string 501 to the drawn configuration. The draw force can optionally be measured as the force on the flexible tension member 585 when the string carrier 480 is in the drawn position (See
Turning back to
A dry fire lockout biasing force is applied by spring 540 to bias dry fire lockout 542 toward the catch 502. Distal end 544 of the dry fire lockout 542 engages the sear 514 in a lockout position 541 to prevent the sear 514 from releasing the catch 502. Even if the safety 522 is disengaged from the sear 514, the distal end 544 of the dry fire lockout 542 retains the sear 514 in the cocked position 524 to prevent the catch 502 from releasing the draw string 501.
As best illustrate in
To cock the crossbow 400 again the string carrier 480 is moved forward to location 483 (see
The cocking mechanism 484 includes a rotating member such as the spool 560, with a flexible tension member, such as for example, a belt, a tape or webbing material 585, attached to pin 587 on the string carrier 480. As best illustrated in
A pair of pawls 572A, 572B (“572”) include teeth 574 (see
In operation, the user presses the release 576 to disengage the pawls 572 from the spool 560 and proceeds to rotate the cocking handle 454 to move the string carrier 480 in either direction 482 along the rail 402 to cock or de-cocking the crossbow 400. Alternatively, the crossbow 400 can be cocked without depressing the release 576, but the pawls 572 will make a clicking sound as they advance over the gear teeth 568.
Upper power cables 610A are attached to the power cable, bracket 608 at upper attachment points 612A and to power cable attachments 462A on the cams 440 (see also
In the illustrated embodiment the attachment points 612A, 612B for the respective power cables 610 are located on opposite sides of the center rail 402. Consequently, the power cables 610 do not cross over the center rail 402. As used herein, “without crossover” refers to a cabling system in which power cables do not pass through a vertical plane bisecting the center rail 402.
As best illustrated in
In the illustrated embodiment the draw string journal 464 rotates between about 270 degrees and about 330 degrees, and more preferably from about 300 degrees to about 360 degrees, when the crossbow 400 is drawn from the released configuration 600 to the drawn configuration 620. In another embodiment, the draw string journal 464 rotates more than 360 degrees (see
The sear 514 is biased by spring 519 to retain the catch 502 in the closed position 504. The safety 522 operates as discussed in connection with
Spring 540A biases dry fire lockout 542A toward the catch 502. Distal end 544A of the dry fire lockout 542A engages the sear 514 in a lockout position 541 to prevent the sear 514 from releasing the catch 502. Even if the safety 522 is disengaged from the sear 514, the distal end 544A of the dry fire lockout 542A locks sear 514 in the closed position 504 to prevent the catch 502 from releasing the draw string 501.
As illustrated in
In the illustrated embodiment; the portion 543A on the dry fire lockout 542A is positioned behind the draw string location 501A. As used herein, the phrase “behind the draw string” refers to a region between a draw string and a proximal end of a crossbow. Conventional flat or half-moon nocks do not extend far enough rearward to reach the portion 543A of the dry fire lockout 542A, reducing the chance that non-approved arrows can be launched by the crossbow 400.
Upper roller 652 is located near the entrance of the arrow capture recess 650. The upper roller 652 is configured to rotate in the direction of travel of the arrow 416 as it is launched. That is the axis of rotation of the upper roller 652 is perpendicular to a longitudinal axis of the arrow 416. The upper roller 652 is displaced within the slot in a direction generally perpendicular to the arrow 416, while spring 654 biases the upper roller 652 in direction 656 against the arrow 416. As best illustrated in
In the illustrated embodiment, the clip-on nock 417 must be fully engaged with the draw string 510A near the rear of the arrow capture recess 650 to disengage the dry fire lock out 542A. In this configuration (see
In one embodiment, the lower angled surfaces 658 do not support the arrow 416 in the arrow capture recess 650 unless the clip-on nook 417 is used. In particular, the upper angled surfaces 660 prevent the nock 417 from rising upward when the crossbow 400 is fired, but the arrow 417 tends to slide downward off the lower angled surfaces 658 unless the clip-on nock 417 is fully engaged with the draw string 510A.
By contrast, prior art crossbows typically include a leaf spring or other biasing structure to retain the arrow against the rail. These devices tend to break and are subject to tampering, which can compromise accuracy.
In an alternate embodiment, the drive shaft 564 is three discrete pieces 505A, 565B, 565C connected by torque control Mechanisms located in housings 567A, 567B. A torque control mechanism 722 generally as illustrated in
The string carrier 480 hits a mechanical stop when it is fully retracted, which corresponds to maximum draw string 501 tension. Tension on the draw string 501 is highly repeatable and uninform throughout the string system due to the operation of the string carrier 480. Further pressure on the cocking handle 720 causes the coupling 724 to slip within the head 729, preventing excessive torque on the cocking mechanism 484 and tension on the flexible tension member 585.
As best seen in
As best seen in
A variety of conventional cocking ropes 810 can releasably engage with the pulleys 804. The hooks found on conventional cocking ropes are not required. As best illustrated in
It will be appreciated that a variety of different cocking rope configurations can be used with the string carrier 480, such as disclosed in U.S. Pat. No. 6,095,128 (Bednar); U.S. Pat. No. 6,874,491 (Bednar); U.S. Pat. No. 8,573,192 (Bednar et al.); U.S. Pat. No. 9,335,115 (Bednar et al.); and 2015/0013654 (Bednar et al.); which are hereby incorporated by reference.
In one embodiment, the cocking ropes 810 retract into handles 812 for convenient storage. For example, protrusions 826 on handles 812 can optionally contain a spring-loaded spool that automatically retracts the cocking ropes 810 when not in use, such as disclosed in U.S. Pat. No. 8,573;192 (Bednar et al.). In another embodiment, a retraction mechanism for storing the cocking ropes when not in use are attached to the stock 408 at the location of the anchors 816 such as disclosed in U.S. Pat. No. 6,874,491 (Bednar). In another embodiment, a cocking rope retraction system with a spool and crank handle can be attached to the stock 408, such as illustrated in U.S. Pat. No. 7,174,884 (the '884 Kempf Patent”).
In operation, when the draw string 501 is in the released configuration 600 the user slides the string carrier 480 forward along the rail into engagement with the draw string 501. The catch 502 (see e.g.,
In the embodiment illustrated in
In order to de-cock the crossbow 400, the-user pulls the handles 812 to retract the string carrier 480 toward the stock 408 a sufficient amount to disengage the hook 818 from the pin 819. In one embodiment, the user rotates the release lever 820 in direction 821 about 90 degrees. The release lever 820 biases the hook 818 in direction 822, but the force 824 prevents the hook from moving in direction 822. The user then pulls the handles 812 toward the stock 408 to remove the force 824 from the hook 818. Once the pin 819 clears the hook 818 the biasing force applied by the release lever 820 moves the hook 818 indirection 822. The user can now slowly move the string carrier 480 toward the released configuration 600.
As illustrated in
In particular; when in the drawn configuration tension forces on the draw string 501 on opposite sides of the string carrier 480 are substantially the same, within less than about 1.0% and more preferably less than about 0.5%, and most preferably less than about 0.1%. Consequently, cocking and firing the crossbow 400 is highly repeatable.
To the extent that manufacturing variability creates inaccuracy in the crossbow 400, any such inaccuracy are likewise highly repeatable, which can be compensated for with appropriate windage and elevation adjustments in the scope 414 (See
Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within this disclosure. The upper and lower limits of these smaller ranges which may independently be included in the smaller ranges is also encompassed within the disclosure, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either both of those included limits are also included in the disclosure.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to these described herein can also be used in the practice or testing of the various methods and materials are now described. All patents and publications mentioned herein, including those cited in the Background of the application, are hereby incorporated by reference to disclose and described the methods and/or materials in connection with which the publications are cited.
The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present disclosure is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed.
Other embodiments are possible. Although the description above contains much specificity, these should not be construed as limiting the scope of the disclosure, but as merely providing illustrations of some of the presently preferred embodiments. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of this disclosure. It should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes disclosed. Thus, it is intended that the scope of at least some of the present disclosure should not be limited by the particular disclosed embodiments described above.
Thus the scope of this disclosure should be determined by the appended claims and their legal equivalents. Therefore, it will be appreciated that the scope of the present disclosure fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the present disclosure is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” All structural, chemical, and functional equivalents to the elements of the above-described preferred embodiment that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved by the present disclosure, for it to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims.
Claims
1. A crossbow comprising:
- a center rail including a rail body and a riser;
- a first flexible limb coupled to the riser;
- a second flexible limb coupled to the riser;
- a first cam mounted to the first flexible limb and rotatable around a first cam axis, the first cam including: a first draw string journal defining a first draw string plane of rotation perpendicular to the first cam axis, and a first power cable take-up journal extending in a direction perpendicular to the first draw string plane of rotation;
- a second cam mounted to the second flexible limb and rotatable around a second cam axis, the second cam including: a second draw string journal defining a second draw string plane of rotation perpendicular to the second cam axis, and a second power cable take-up journal extending in a direction perpendicular to the second draw string plane of rotation;
- a draw string received in the first draw string journal and in the second draw string journal and secured to the first cam and the second cam;
- a first power cable coupled to the center rail and received in the first power cable take-up journal; and
- a second power cable coupled to the center rail and received in the second power cable take-up journal,
- wherein the first cam and the second cam are configured so that the draw string unwinds from the first draw string journal and the second draw string journal as the crossbow is moved from a released configuration to a drawn configuration,
- wherein the first cam is configured to rotate more than 270 degrees about the first cam axis as the crossbow is moved from the released configuration to the drawn configuration,
- wherein the second cam is configured to rotate more than 270 degrees about the second cam axis as the crossbow is moved from the released configuration to the drawn configuration,
- wherein the first power cable take-up journal of the first cam is configured to displace the first power cable away from the first draw string plane of rotation as the crossbow is moved from the released configuration to the drawn configuration, and
- wherein the second power cable take-up journal of the second cam is configured to displace the second power cable away from the second draw string plane of rotation as the crossbow is moved from the released configuration to the drawn configuration.
2. The crossbow of claim 1, wherein the first cam is configured to rotate 360 or fewer degrees about the first cam axis as the crossbow is moved from the released configuration to the drawn configuration, and
- wherein the second cam is configured to rotate 360 or fewer degrees about the second cam axis as the crossbow is moved from the released configuration to the drawn configuration.
3. The crossbow of claim 2, wherein the first power cable take-up journal defines a length that accommodates between 270 degrees and 360 degrees of rotation of the first cam, and wherein the second power cable take-up journal defines a length that accommodates between 270 degrees and about 360 degrees of rotation of the second cam.
4. The crossbow of claim 1, wherein the first power cable take-up journal includes a first portion and a second portion spaced apart from the first portion in the direction perpendicular to the first draw string plane of rotation, and
- wherein the second power cable take-up journal includes a first portion and a second portion spaced apart from the first portion in the direction perpendicular to the second draw string plane of rotation.
5. The crossbow of claim 4, wherein the first power cable has a first power cable width and the first portion of the first power cable take-up journal is spaced apart from the second portion of the first power cable take-up journal by a distance greater than the first power cable width in the direction perpendicular to the first draw string plane of rotation, and
- wherein the second power cable has a second power cable width and the first portion of the second power cable take-up journal is spaced apart from the second portion of the second power cable take-up journal by a distance greater than the second power cable width in the direction perpendicular to the second draw string plane of rotation.
6. The crossbow of claim 1, wherein the center rail further includes a power cable bracket, wherein the first power cable and the second power cable are attached to the power cable bracket.
7. The crossbow of claim 6, wherein the power cable bracket substantially surrounds a projectile axis of the crossbow.
8. The crossbow of claim 7, wherein the power cable bracket is positioned forward of the first cam axis and the second cam axis along the projectile axis of the crossbow.
9. The crossbow of claim 6, wherein the power cable bracket is separate from and coupled to the rail body.
10. The crossbow of claim 6, wherein the power cable bracket is positioned forward of the first cam axis and the second cam axis along a projectile axis of the crossbow.
11. The crossbow of claim 1, wherein the first power cable is attached to a first static attachment point to couple the first power cable to the center rail and the second power cable is attached to a second static attachment point to couple the second power cable to the center rail, and
- wherein the second static attachment point is located on an opposite side of the rail body from the first static attachment point.
12. The crossbow of claim 1, wherein the first power cable has a first power cable width and the first power cable take-up journal is configured to displace the first power cable away from the first draw string plane of rotation a distance greater than the first power cable width in the direction perpendicular to the first draw string plane of rotation, and
- wherein the second power cable has a second power cable width and the second power cable take-up journal is configured to displace the second power cable away from the second draw string plane of rotation a distance greater than the second power cable width in the direction perpendicular to the second draw string plane of rotation.
13. The crossbow of claim 1, wherein the first draw string plane of rotation and the second draw string plane of rotation are coplanar.
14. The crossbow of claim 1, further comprising:
- a first axle mount fixedly attached to the first flexible limb, wherein the first cam is rotatably coupled to the first axle mount so that the first cam axis is offset from a first limb end by a fixed offset, and
- a second axle mount fixedly attached to the second flexible limb, wherein the second cam is rotatably coupled to the second axle mount so that the second cam axis is offset from a second limb end by a fixed offset.
15. The crossbow of claim 1, wherein the first cam axis passes through the first flexible limb and wherein the second cam axis passes through the second flexible limb.
16. A method of operating a crossbow including a center rail having a rail body and a riser, a first flexible limb coupled to the riser, a second flexible limb coupled to the riser, a first cam mounted to the first flexible limb and rotatable around a first cam axis, the first cam including a first draw string journal defining a first draw string plane of rotation perpendicular to the first cam axis and a first power cable take-up journal extending in a direction perpendicular to the first draw string plane of rotation, a second cam mounted to the second flexible limb and rotatable around a second cam axis, the second cam including a second draw string journal defining a second draw string plane of rotation perpendicular to the second cam axis and a second power cable take-up journal extending in a direction perpendicular to the second draw string plane of rotation, a draw string received in the first draw string journal and in the second draw string journal and secured to the first cam and the second cam, a first power cable coupled to the center rail and received in the first power cable take-up journal, and a second power cable coupled to the center rail and received in the second power cable take-up journal, the method comprising the steps of:
- rotating the first cam and the second cam more than 270 degrees to unwind the draw string from the first draw string journal and the second draw string journal as the crossbow is moved from a released configuration to a drawn configuration;
- wrapping the first power cable onto the first power cable take-up journal and displacing the first power cable away from the first draw string plane of rotation as the crossbow is moved from the released configuration to the drawn configuration; and
- wrapping the second power cable onto the second power cable take-up journal and displacing the second power cable away from the second draw string plane of rotation as the crossbow is moved from the released configuration to the drawn configuration.
17. The method of operating a crossbow of claim 16, further comprising rotating the first cam and the second cam 360 or fewer degrees to unwind the draw string from the first draw string journal and the second draw string journal as the crossbow is moved from the released configuration to the drawn configuration.
Type: Application
Filed: Mar 1, 2023
Publication Date: Jun 29, 2023
Applicant: Ravin Crossbows, LLC (Superior, WI)
Inventor: Craig YEHLE (Winona, MN)
Application Number: 18/116,153